1. Field of the Invention
The present invention relates to a method and apparatus for encoding and decoding an audio signal, and more particularly, to a method and apparatus for efficiently encoding and decoding both an audio signal and a speech signal by using few bits.
2. Description of the Related Art
Audio signals, such as speech signals or music signals, can be classified into a low frequency signal, which is in a domain smaller than a predetermined frequency, and a high frequency signal, which is in a domain higher than the predetermined frequency, by dividing the audio signals based on the predetermined frequency.
Since the high frequency signal is not relatively important compared to the low frequency signal for recognizing the audio signals due to a hearing characteristic of a human being. Accordingly, spectral band replication (SBR) is developed as a technology for encoding/decoding an audio signal. According to SBR, an encoder encodes a low frequency signal according to a conventional encoding method, and encodes a part of information of a high frequency signal by using the low frequency signal. Also, a decoder decodes the low frequency signal according to a conventional decoding method, and decodes the high frequency signal by using the low frequency signal decoded by applying the part of information encoded in the encoder.